Preoral cavity, bounded ventrally by posteriorly directed labrum, dorsally by ventral surface of cephalon just behind mouth, and laterally by paragnaths and mandibles [Moore and McCormick, 1969].
Preoral cavity, bounded ventrally by posteriorly directed labrum, dorsally by ventral surface of cephalon just behind mouth, and laterally by paragnaths and mandibles [McLaughlin, 1980].
(Order Diplostraca):
Large preoral cavity formed by upper lip (labrum) extending over mouth. Tips (molar processes) of mandibles extend into atrium oris [Stachowitsch, 1992].
(Class Cephalocarida):
Large preoral cavity formed by labrum extending over mouth. Mandibles (and to a lesser extent the endites or gnathobases of maxillules) extend into atrium oris [Stachowitsch, 1992].
(Class Remipedia):
Cavity around mouth formed by projecting posterior margin of labrum and paragnaths; masticatory ends (incisor process, lacinia mobilis, molar process) of mandible project into atrium oris [Stachowitsch, 1992].
Crustacea glossary. Natural History Museum of Los Angeles County. 2011.